Validity of Quantitative Research
Given that the primary focus of my research involves crime rates, the level of measurement required is interval. As interval level of measurement describes variables that have differences between them numerically. Therefore, all crime rates are interval level measurements. The purpose of content validity is to measure the significant variables within the research. Further it can be used to quantify the adequate sampling of substance areas of questionnaires to determine content relevance. Content validity requires two logical estimations based upon objective evaluation: a degree of measurability given to each variable that illustrates the important qualities and the set of variables that depict all viewpoints of the qualities. “Content validity is obtained from three sources: literature, representatives of the relevant populations, and experts" (Burns N., & Grove S.K. 1993). Content validity can occur in a two step process involving the developmental and the judgmental stages. There is not definitive objective methodology for determining the content validity. However, “content validity in the judgment stage is based on quantitative evidence” (Wilson, H.S. 1989). “To examine the content validity in judgment stage, professional subjective judgment is required to determine the extent to which the scale was designed to measure a trait of interest” (Nunnally, J.C. 1978). “Ghiselli pointed out that content validity depends on subjective or professional judgment” (Waltz, C.F., & Bausell, R.B. 1983). “Content validity is a subjective judgment of experts about the degree of relevant construct in an assessment instrument. However, inclusion of at least five experts in that field” (Burns, N., & Grove, S.K. 1993) or “five to ten experts would be useful to judge the content domains of a scale through use of rating scales” (Wilson, H.S. 1989). Developed by Waltz and Bausell (1983), the Content Validity Index (CVI) assesses variables by evaluating each individually
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